Can openers

ABSTRACT

A can opener of the type in which the can is opened by cutting through an outer part of the rim joining the lid with the main body of the can. Cam means (51) are arranged to engage outside wall of the can immediately beneath the rim, the engagement underneath the rim moving the cam means and cutter wheel (40) against resilient means (54) to a position such that the cutter wheel makes its cut at a substantially constant predetermined distance on the rim. The drive wheel can have an outer cylindrical surface which is toothed and its lower edge bevelled or chamfered. To reduce friction, the shaft supporting the drive wheel may be journaled within a metal sleeve supported by the body of the can opener, the outer surface of the shaft and the inner surface of the sleeve mate at positions adjacent the ends of the sleeve so as to provide good rotational support for the shaft and intermediate those positions a gap being provided between the outer surface of the shaft and the inner surface of the sleeve to avoid contact between the shaft and sleeve. The cutter wheel may be supported by an arcuate support wall (66) during cutting.

This invention relates to can openers. In particular the inventionrelates to a can opener of the type which will remove the lid of a canby making a cut through the outer part of the join between the lid andthe wall of the can.

An example of such a can opener is shown in U.S. Pat. No. 4,734,986 towhich reference is directed. The can opener shown in that Patent makes athin cut around the rim through the material of the lid itself where itis folded over and around the top of the upright wall of the can. Thelid is then removed from the rest of the can by means of a grippingmechanism which levers the lid from the remainder of the can.

Such a can opener has a number of advantages over existing can openersin that the remaining top edge of the opened can is not sharp. Thus whatis in fact exposed is the turned over top edge of the side wall of thecan and that is smooth and so unlikely to cut a user who may hold it ortouch it. Also the top edge is still well reinforced by the remainingfolded-over material of the can and so, when the can is gripped, itstill retains it's shape. Further, since the cut takes place only on theoutside of the can wall and there is no penetration through into theinterior of the can, no metal filings or the like will contaminate thecontents of the can and the possibly unhygienic cutting knife does notcontact the contents of the can.

As explained in the above noted Patent, there are problems in providingthe necessary close tolerances in the construction of the can opener andin maintaining them during a cutting operation and the above Patent aimsto provide one way of achieving this. Good results can be achieved withcan openers according to this Patent but the results arc not alwaysconsistent.

There are a wide range of shapes and sizes of can on the market, and wehave found that there are large differences in the dimensions of thefolded over seam joining the lid to the rest of the can. The can openershown in the above noted Patent does not provide a way of dealing withthese differences.

It is therefore an object of the present invention in one aspect toachieve this.

According to the invention in one aspect there is provided a can openerfor opening a can having a lid joined to a main body by a rim, in whichthe can is opened by cutting through an outer part of the rim joiningthe lid with the main body of the can, in which the can opener comprisesa rotatably supported cutter wheel for engaging and cutting the saidouter part of the rim, a rotatable drive wheel for engaging the innerpart of the rim, means for gripping the rim between the cutter wheel anddrive wheel so that, upon rotation of the drive wheel, the can openerorbits around the rim of the can and the cutter wheel can complete a cutaround the outer part of the rim, resilient means for allowing thecutter wheel to move resiliently in an axial direction along its axis ofrotation, and cam means joined to the cutter wheel and axially spacedfrom the cutter wheel by a predetermined amount, the cam means beingarranged to engage the, underside of the rim, the engagement underneaththe rim moving the cam means and the cutter wheel against the resilientmeans to a position such that the cutter wheel makes its cut at asubstantially constant predetermined distance up the rim from its lowerend.

We find that with such a can opener a consistent good result can beachieved since, irrespective of the shape and size of the can or of thesize and depth of the rim, a cut can be achieved in the best positionfor lid removal. In practice, or example, we have measured the depth ofthe rim in a wide variety of commercially available cans and have foundthat this depth can vary from about 2.5 mm to about 3.5 mm, and is notby any means consistent from one can of the same product to another.This problem is avoided by the invention, however, since the cam meanswill engage under the rim and if necessary move the cutter wheel againstthe resilient means to a set position above the lower edge of the rim.Further, if there is any variation in the rim depth as the opener orbitsaround the can, this will also be accommodated.

In one preferred embodiment of the invention the cam means comprise acircular flange having an upper face which is slightly inclined relativea plane radial to the axis of the flange and is arranged to engage underthe rim, the inclined upper face moving the circular flange and theassociated cutter wheel against the resilient means as the flange isforced in beneath the rim when the rim is gripped between the cutterwheel and drive wheel and the cutting edge of the cutter wheel is forcedto penetrate through the outer part of the rim. The circular flange hasa larger diameter than the cutter wheel since it engages the uprightwall of the main body of the can which is of necessity of smallerdiameter than the rim. The difference in diameters can, however, bechosen to ensure that the cutting edge of the cutter wheel does notpenetrate significantly beyond the material of the outer par of the rim.

The circular flange and cutter wheel can be formed from a single pieceof material or could be made separately and then joined so that theywill rotate together and move together longitudinally of theirrotational axis. Conveniently, they are jointly mounted about a commonaxle on which they rotate.

The resilient means can, in one simple embodiment of the invention,comprise a resilient rubber washer mounted between the cam means and astationary support. Thus, as the cam means move the cutter wheel down tofit the can means beneath a rim, that washer will be compressed, andwhen a cutting operation is over then the compressed washer will restorethe cutter wheel to its rest position along its rotational axis.

As explained in the above noted United States Patent, there are problemsin providing the necessary close tolerances in the support of thecutting knife of the can opener and the Patent aims to provide one wayof achieving this. We have found, however, that to accommodate differenttypes of tin, the cutting knife cannot be supported in the way definedin that Patent. However the cutting knife still needs good support andit is, therefore, an object of another aspect of the present inventionto achieve this.

According to another aspect of the invention there is provided a canopener for opening a can having a lid joined to a main body by a rim, inwhich the can is opened by cutting through an outer part of the rimjoining the lid with the main body of the can, in which the can openercomprises a cutter wheel for engaging and cutting the said outer part ofthe rim, a rotatable drive wheel for engaging the inner part of the rim,a pair of body members pivoted to one another and arranged, uponpivoting relative one another, to move the drive wheel and cutter wheeltowards and away from one another respectively to allow the can openerto be fitted over the rim of a can to be opened and to grip the rimbetween the cutter wheel and drive wheel so that, upon rotation of thedrive wheel, the can opener orbits around the rim of the can and thecutter wheel can complete a cut around the outer part of the rim, thecutter wheel being rotatably supported on a shaft upstanding from one ofthe body members, a circular flange of diameter greater than the cutterwheel also being supported on the said shaft, and an arcuate supportwall upstanding from the said one body member and being centered on theaxis of rotation of the cutter wheel, the circular flange being arrangedto bear against the support wall to assist in supporting the shaft andcutter wheel during cutting of the rim of a can.

We have found that with such an arrangement the rotational axis of thecutter wheel can be maintained accurately even under high cutting loads.Generally the body members will be made of synthetic plastics materialand so the axis of tho shaft, which may be integrally formed with thesaid one body member or may be a separately member, will be liable todistort under load because the plastics material of the said body memberwill be incapable of resisting this distortion. It is undesirable thatthis occurs since then the required close cutting tolerances will belost, but this distortion is kept to a minimal level by the supportgiven to the shaft. Thus, the arcuate support wall buttresses thecircular flange mounted on the shaft and so helps to prevent bending ofthe shaft under load, particularly if the circular flange is mountedoutwardly of the cutting edge.

In addition we have found that it can be desirable for the two pivotedbody members to have at least one cooperating flange and recess the suchthat engagement of the flange in the recess reinforces the said one bodymember by the other. This reinforcement of one body member by the otherusing the flange and recess arrangement reduces the chance of an overalldistortion of the said one body member provided with the shaft and thearcuate support wall.

In one embodiment the body members have integral handles extendinggenerally away from the axis of pivoting of the two body members. Then,at the edge of at least one handle where it abuts tho other body member,there may be provided a recess into which a corresponding arcuate shapedflange of the other handle fits. It is preferred that a pair ofcooperating flanges and recesses be provided. Thus the edge of eachhandle where it abuts the other body member, may have a flange extendinginto engagement with a corresponding recess in the other body member.

We have found that it is of importance that there be close tolerances inthe positioning of the cutting knife on a can to be opened and it is,therefore, an object of another aspect of the invention to achieve this.

According to another aspect of the invention there is provided a canopener for opening a can having a lid joined to a main body by a rim, inwhich the can is opened by cutting through an outer part of the rimjoining the lid with the main body of the can, in which the can openercomprises a cutter wheel for engaging and cutting the said outer part ofthe rim, a rotatable drive wheel for engaging the inner part of the rim,a pair of body members pivoted to one another and having integralhandles extending generally in a direction away from the axis ofpivoting, the body members being arranged, upon pivoting relative oneanother, to move the drive wheel and cutter wheel towards and away fromone another respectively to allow the can opener to be fitted over therim of a can to be opened and to grip the rim between the cutter wheeland drive wheel so that, upon rotation of the drive wheel, the canopener orbits around the rim of the can and the cutter wheel cancomplete a cut around the outer part of the rim, one body membersupporting the cutter wheel and having a substantially flat surface inthe region of the nip between the cutter wheel and the drive wheel, theintegral handle of the other body member having an undersurface which issubstantially flat and also substantially in the same plane as thesubstantially flat surface on the said one body member, whereby when thebody members and their integral handles are pivoted to allow the canopener to be fitted over the rim of a can, those two surfaces will reston the top of the rim of a can and will align the axis of the cutterwheel so that at least in the plane containing them it is parallel withthe upright axis to the can.

This has the advantage that the circular cutting edge on the cuttingwheel will be accurately aligned in the direction of the cut to be madeand ensures that, as the body members and their handles are pivotedtogether to bring the drive wheel and cutter wheel close together togrip the rim, the initial penetration of the rim by the cutting edgewill be accurately aligned in the desired direction of the cut to bemade. As a result an improved consistency of cutting from one can toanother can be achieved.

It is preferred that the said one body member which supports the cutterwheel also have a further contact surface on the opposite side of thedrive wheel from the cutter wheel. This contact surface should be spaceddownwardly from the said substantially flat surface on the said one bodymember by an amount substantially equal to the inner depth of the rim,that is to say the height of the rim above the central top region of thelid. Thus, this further contact surface will rest on the top of the lidand ensure that the axis to the cutter wheel is also aligned so as toparallel with the upright axis of the can in a direction transverse to aplane containing them. In effect with this additional contact surfacethere is a three point contact with the can when the body members arepivoted to their open position and the can opener placed over the rim ofa can to opened which guides the user so that, as the handles areclosed, the cutter wheel is kept in correct alignment to penetrate therim.

We have also found that can openers of the type shown in the aboveUnited States Patent have difficulty in coping with cans having smallradius corners. The problem seems to be that the drive wheel whichdrives the opener around the can slips and fails to moves the canopener.

Therefore in accordance with one embodiment of the invention the drivewheel has an outer cylindrical surface which is serrated to allow it togrip into the material of the rim to assist in driving the can openeraround the can, and the lower edge, that is to say the edge adjacent tothe lid of the can when in use, of the outer cylindrical surface of thedrive wheel is bevelled.

By providing this bevel we have surprisingly found that a more reliabledrive action is achieved even through the effect of the bevel isactually to reduce the area of contact between the drive wheel and therim of the can. In particular it seems that in tight corners of a can,the rim is often distorted and not upright so that with a drive wheelhaving a completely cylindrical outer face only a line contact isachieved anyhow whereas with a can opener according to this aspect ofthe invention a much larger area of contact can be achieved between thedrive wheel and the rim of the can in tight radius corners.

Additionally we have found that it is desirable to keep the tolerancesof the depth of the cut made very close to the desired amount so thatthe cutter wheel does not penetrate into the rim significantly furtherthan the outer layer of material. Further the gripping force between thecutter wheel and drive wheel should desirably not distort the rim of thecan. The bevel also has the advantage of ensuring that the outerperipheral surface of the drive wheel can fit closely to the inner faceof the rim without significantly distorting the rim.

The angle of the bevel is preferably about 45° but could, for example,range from 30° to 60° to the axis of the drive wheel. Preferably alsothe bevel extends radially at least equal to the depth of theserrations.

We have also found that it is desirable that the serrations in the drivewheel be relatively shallow since if the serrations are too large theyare liable to bite into the rim of the can and damage it and lock thelayers of the rim together, with the result that it may not be easy tolever off the severed lid. Preferably therefore the maximum radial depthof the teeth or serrations is no more than 1.5 mm and most preferablythe radial depth is no more than 1 mm. Generally speaking thereforethere will be a relatively large number of shallow, closely spacedserrations.

Another problem we have encountered with can openers of this type isthat the forces required to make the cut and advance the can openeraround the top of the can tend to be quito high. Therefore anything onecan do to reduce the effort required is clearly highly desirable.

Generally speaking the main body of the can opener itself is made ofsynthetic plastics material whilst the shaft carrying the driving gearis made of metal and usually steel. As a result there are relativelyhigh friction forces between the shaft and the body of the plasticsmaterial and it is an object of a further aspect of the invention toovercome this.

According to a further aspect of the invention there is provided a canopener of the type which opens the can by making a cut from the outsidethrough the outer layer of material of the rim and which has a drivewheel which engages the inside of the rim around the can lid and uponrotation drives the can opener around the can, and in which the drivewheel is supported by a metal shaft which is rotatably journaled withina metal sleeve supported by the body of the can opener, the outersurface of the shaft and the inner surface of the sleeve mate atpositions adjacent the ends of the sleeve so as to provide rotationalsupport for the shaft and intermediate those positions a gap beingprovided between the outer surface of the shaft and the inner surface ofthe sleeve to avoid contact between the shaft and sleeve so as to reducefrictional forces upon rotation of the shaft relative the sleeve.

With such an arrangement the frictional forces between the two parts ofthe metal shaft which engage the sleeve and the sleeve itself are keptquite small and unnecessary frictional forces are avoided by providingthe gap between the central portion of the shaft and the sleeve so thatthere is no frictional force at all. Thus, it is not necessary for thatcentral portion to contact the sleeve to provide good rotational supportprovided the ends of the sleeve mate with the shaft. In addition, theresulting recess which is formed between the interior surface of thesleeve and the outer surface of the shaft can be filled with a lubricantsuch as a grease to reduce frictional contact in the mating regions.

The interior surface of the sleeve and external surface of the shaft arepreferably of hardened steel so as to ensure that frictional forces arekept to a minimum. For example, they should be hardened and tempered toa specification according to Rockwell Hardness C scale (HRC) within therange of 45 to 56.

According to one simple embodiment of this aspect of the invention, thesleeve is of constant internal cross-sectional diameter whilst the shafthas a region of reduced diameter between the areas of intended contactwith the sleeve so as to provide the said gap.

The invention will now be illustrated, by way of example, with referenceto the accompanying drawings, in which:

FIG. 1 is a side elevation of one form of can opener according to theinvention;

FIG. 2 is an underneath view;

FIG. 3 is an enlarged cross-sectional detail taken along the line 3--3of FIG. 2;

FIG. 4 is a side view showing the can opener in use on the first step ofopening a can;

FIG. 5 is an enlarged detail of the area circled in FIG. 4 and marked 5in the case of one can;

FIG. 6 is an enlarged detail similar to FIG. 5 but showing the case of adifferent can;

FIG. 7 is an enlarged cross-sectional detail taken along the line 7--7of FIG. 2;

FIG. 8 is an underneath view showing the can opener in the openedposition;

FIG. 9 is an enlarged cross-sectional detail showing the second step inthe removal of the can lid;

FIG. 10 is a detail similar to FIG. 9 showing the lid being removed;

FIG. 11 is a view similar to FIG. 3 of another form of can openeraccording to the invention;

FIG. 12 is a view similar to FIG. 5 of that said another form of canopener; and

FIG. 13 is a view similar to FIG. 3 of yet another form of can openeraccording to the invention.

The can opener 10 shown in FIGS. 1 to 10 of the drawings comprises apair of handles 12 and 14 which are integrally formed with body portions16 and 18, respectively. The latter are pivoted to one another about aspigot 20 (FIG. 3) which is integral with the body portion 16 and whichextends into a corresponding opening in the body portion 18.

A spindle 24 passes through the spigot 20, the spindle being formed atone side with a drive wheel 26. This has on its outer face, serrations,teeth or the like to allow it to grip the inside of a can rim 29 sothat, when it is rotated, it will drive the can opener 10 around a can30 to be opened. At its other side, the spindle is joined to a crank 32by means of which the wheel 26 can be manually rotated.

As best seen in FIG. 3, the axis 34 of the spindle 24 is offset from theaxis 36 of the spigot 20. In this way, when the handles 12 and 14 areopened up to the position shown in FIG. 8 by pivoting the portions 16and 18 about the spigot 20, the drive wheel 26 is moved away from acutter wheel 40 and so can be placed over the rim 29 of a can to beopened, and conversely, when the handles are brought together as shownin FIG. 2 and grasped in the hand of a user, the drive wheel 26 is movedin closer to the cutter wheel 40 so that the rim 29 of the can isgripped between the two.

Integrally formed with the body portion 18 is an upstanding shaft 44(FIGS. 6 and 7) on which the cutter wheel 40 is idly and rotatablymounted. The cutter wheel comprises a circular cutting edge 46 and anintegral circular flange 48. The outer cylindrical face 49 of this is ofslightly larger diameter than the cutting edge 46 so that the face 49can bear against an upright side wall 50 of the can 30. The flange alsohas a slightly inclined cam edge 51 formed on its upper face which isdesigned to engage below the rim 29 of a can. This edge 51 is angled atabout 80° to the axis of rotation of the cutter wheel. It could howeverbe angled say from 75° to 85° to the axis of rotation. It is, howeverimportant that the edge 51 penetrate under the rim 29 which willnormally be 1 to 1.5 mm larger in diameter than the side wall 50 andmove the cutter wheel 40 is required as explained below.

The cutter wheel 40 is held in place on the shaft 44 by an end cap 52riveted or screwed to the shaft 44. However, between the end cap 52 andthe wheel 40 is a resilient washer 54 of elastomeric material, and inturn between the washer 54 and the wheel 40 is a thin metal washer 55.

Referring to FIG. 5, this shows in detail the construction of the rim 29of a can 30. The top of the side wall 50 of a can is bent over in theshape of a "U" whilst the edge of a lid 62 is bent up around the insideof the side wall, over the top of the bent-over side wall, down aroundthe outside of that bent-over portion in a region 63 and finally its endis bent up inside and so trapped by the bent-over top of the side wall.In a can opener of the invention it is the bent-over portion of the lid62 in the region 63 which is cut by the cutting edge 46.

The surface 64 of the body portion 18 between the cutter wheel 40 anddrive wheel 26 is flat and transverse to the axis of the rotation of thetwo wheels. In addition and as best seen in FIGS. 1 and 4 theundersurface 65 of the handle 14 is in the same plane as that surface64. Therefore when the body portions and their respective handles arepivoted open to enable a can rim 29 to enter between the drive wheel 26and cutter wheel 40, the top of the rim 29 can rest on the surface 64.Because this is flat right across the width of the body portion 16 theresting of the surface on the rim will align the axis 45 with theupright axis of the can. In addition with the handles 12 and 14 openedup as in FIG. 8 or even further than that, the surface 65 canadditionally rest on the rim 29 (shown diagrammatically by the brokenline 29 in FIG. 8) and assist in ensuring this alignment.

At the outer end of the body member as formed an integral downwardlyextending lug 76 having a lower flat contact surface 78. This extendsdownwardly by an amount approximately equal to the height of the rim 28above the top surface of the lid 62. In this way, by resting the contactsurface 76 on the lid 62 when the can opener is placed over the rim 29of a can to be opened, one can ensure that the axis 45 of rotation ofthe cutter wheel 40 is accurately parallel to the upright axis of thecan.

In the removal of the lid 62, the handles 12 and 14 are first of allopened up by pivoting them apart in the direction of the arrows 70 (FIG.2) to the position shown in FIG. 8. This opens up a gap between thedrive wheel 26 and the cutter wheel 40 as has been described. The canopener can then be placed over the top of a can 30 with the rim 29between the wheels 26 and 40. The handles are then brought to theirclosed position as shown in FIG. 2. The handles are then brought totheir closed position as shown in FIG. 2. This causes the rim 29 to begripped between the wheels 26 and 40 and the teeth or serrations 27 ofthe drive wheel engage tightly with the inside of the rim 29. At thesame time, the cutting edge 46 is forced through the material of the lidin the region 63.

As has been explained above the surface 64 and 65 ensure that thecutting edge 46 is accurately aligned in the direction around the rim 29in which the circular cut is to be made. Also, the contact of thecontact surface 78 with the top of the lid 62 ensures that the cuttingedge 46 enters the material of the lid precisely in a direction at rightangles to the upright side wall 60 of a can.

Next the crank 32 is rotated whilst the user grips the handles 12 and 14with his other hand. The rotation causes the can opener 10 to orbitaround the can and make a complete circular cut through the material ofthe lid in the region 63.

It will be seen best from FIG. 5 that, when the handles are fullyclosed, the edge 51 of the flange 48 has engaged under the lower edge ofthe rim 29, the cylindrical outer face 49 of the flange 48 contactingthe outer face of the side wall 50 of the can. The depth d of a rim 29varies widely from can to can and may even vary around an individualcan. This can lead to inconsistent cutting and so as to avoid this itwill be seen that, if the depth d is greater than the minimum envisagedin FIG. 5, i.e. the situation in FIG. 6, then the cam surface 51 stillengages under the lower edge of the rim 29 but draws the cutter wheel 40downwardly, so compressing the washer 54. The spacing a between thecutting edge 46 and the lower edge of the rim 29 remains constant and isof course fixed by the relative positions of the flange 48 and cuttingedge 46. Consistent cutting results can therefore be achieved.

Once a complete circular cut has been made, the handles 12 and 14 arcopened up and the can released. At the same time, the washer 54 willrestore the cutter wheel to its position shown in FIG. 5 if it was movedaway from this in the sense shown in FIG. 6.

Integrally formed with the body member 18 is an upstanding arcuate wall66. Its axis is centered on the axis of the shaft 44, and it extendsangularly for approximately 180°, half and half on either side of a lineA (see FIG. 2) which is an extension of a line joining the axes of thecutter wheel 40 and drive wheel 26 when the can opener is in theposition shown in FIG. 2. The wall 66 could extend angularly for more orless, e.g. from about 45° to about 220°, half and half on either side ofthe line A. In practice if it extends for more than 180° this can leadto difficulties in assembling the can opener whereas 180° is a preferredextent so that the wall not only supports the shaft to prevent bendingaway in the sense of direct line between the axes of the cutter wheeland drive wheel but also supports the shaft to prevent sideways bendingas the can opener makes a cut.

As best shown in FIGS. 5 and 6, the inside face 68 of the wall has adiameter approximately the same as that of the outer cylindrical face 49of the flange 48. That face 49, therefore, contacts the face 68 and inthis way the wall can buttress the shaft 44 during a cutting operation,so preventing substantial distortion of the shaft 44 and consequentlymisalignment of the cutting edge 46 with the rim 28. This is despite thefact that the body member 18 and its integral shaft 44 are moulded fromsynthetic plastics material.

To further enhance the stiffness of the arrangement, each body member 16and 18 may be provided along its edge with an integral arcuate flange 72which extends into a corresponding shaped slot 74 on the edge of thehandle 12 or 14 of the other body member. Thus the flanges 72 can slideeasily within their respective slots 74 as the handles and body membersarc pivoted. However, when the can opener is in a position for making acut, i.e. the position shown in FIG. 2, the flanges 72 are whollyreceived in their respective slot 74 and the body members 16 and 18 thenbuttress and reinforce one another to prevent twisting and bending ofthe members when under a can opening load. Again this assists in keepingthe cutting edge 46 in the required close tolerances for accurate andconsistent can opening.

Upon removal of the can opener 10 the lid 62 will still appear to beintact on the can. It can be removed by levering it off using amechanism 80, which as best shown in FIG. 2, is provided on one side ofthe body portion 8.

This mechanism 80 is shown in more detail in FIGS. 9 and 10 andcomprises a metal lever arm 82. This is mounted in an outer metal frame83 and hinges about its lower end 84. It is resiliently urged outwardlyby a resilient member 85 and has an integral hook 86. The lattercorresponds in position to the position of the cutting edge 46.Therefore, when the mechanism 80 is placed over the rim of a can asshown in FIG. 9, the lever arm 82 is resiliently retracted until thehook 86 snaps into the cut made in the material of the lid 62 in theregion 64. Now when the whole can opener is levered up, the hook 86forces the severed portion of the lid off from the rest of the can toopen it.

An advantage of a can opener according to the invention is apparent fromFIG. 10 in that the exposed top edge of the can after opening is notsharp since it is not a cut edge but is in fact the turned or bent overtop edge of the side wall 50 of the can.

In the modified form of can opener shown in FIGS. 11 and 12 there isprovided a modified drive wheel 125. Other parts of the can opener canbe the same as described in connection with FIGS. 1 to 10 and similarparts are given similar reference numerals.

As shown in FIGS. 11 and 12, the lower edge 130, that is to say the edgewhich is adjacent to the lid of the can when in use, of the outer face126 of the drive wheel 125 has a chamfer or bevel 131. This chamfer orbevel 131 is at an angle of about 45° and extends to a depth slightlygreater than the serrations or teeth 27.

We have found that by providing this chamfer or bevel 131, the drivewheel 125 gives a better grip when cutting the small diameter corners ofrectangular cans. It seems that a reason for this may be because the rim28 in such corners is often not very upright but is angled outwardly sothat, without the chamfer 31, only the lower edge of the face 126 of thewheel 125 would contact the rim so that the major portion of a serrationor tooth does not contact the rim.

A detail of another modified form of can opener is shown in FIG. 13where the drive spindle 224 differs from that shown in the embodimentsof FIGS. 1 to 12. Other parts of the can opener can be the same asdescribed in connection with either FIGS. 1 to 10 or FIGS. 11 and 12 andsimilar parts are given the same reference numerals as in FIGS. 1 to 10.

Referring to FIG. 13, the drive spindle 224 is rotatably journaled in asteel sleeve 237 embedded within the material of the spigot 20. Atspaced regions 238 and 239 adjacent the ends of the sleeve 237, thespindle 224 has a diameter such that the spindle is a good mating fitwithin the sleeve. In this way good rotational support is provided forthe spindle. In a central region 240, however, the spindle is of reduceddiameter so as to leave a gap 241 between the spindle 224 and sleeve237. This gap could, for example, be of a radial distance of around 0.4mm because there is therefore no contact between the spindle and sleevein this central region, there is therefore no friction created from theregion during rotation of the shaft. Also a lubricating grease can beprovided within the gap 241 for lubrication of the sliding surfaces inthe regions 238 and 239. In these latter regions, however, there is agood mating fit between the interior of the sleeve and the exterior ofthe shaft so that good rotational support is given. Desirably theinterior surface of the sleeve and exterior surface of the shaft havebeen hardened and tempered to HRC of 56 to reduce frictional forces.

I claim:
 1. A can opener for opening a can having a lid joined to a mainbody by a rim, in which the can is opened by cutting through an outerpart of the rim joining the lid with the main body of the can, in whichthe can opener comprises a rotatably supported cutter wheel for engagingand cutting the said outer part of the rim, a rotatable drive wheel forengaging the inner part of the rim, means for gripping the rim betweenthe cutter wheel and drive wheel so that, upon rotation of the drivewheel, the can opener orbits around the rim of the can and the cutterwheel can compete a cut around the outer part of the rim, resilientmeans for allowing the cutter wheel to move resiliently in an axialdirection along its axis of rotation, and cam means joined to the cutterwheel and axially spaced from the cutter wheel by a predeterminedamount, the cam means being arranged to engage the underside of the rim,the engagement underneath the rim moving the cam means and the cutterwheel against the resilient means to a position such that the cutterwheel makes its cut at a substantially constant predetermined distanceup the rim from its lower end.
 2. A can opener as claimed in claim 1 inwhich the cam means comprise a circular flange having an upper facewhich is inclined relative a plane radial to the axis of the flange andis arranged to engage under the rim, the inclined upper face moving thecircular flange and the associated cutter wheel against the resilientmeans as the flange is forced in beneath the rim when the rim is grippedbetween the cutter wheel and drive wheel and the cutting edge of thecutter wheel is forced to penetrate through the outer part of the rim.3. A can opener as claimed in claim 2 in which the circular flange has alarger diameter than the cutter wheel, the difference in diameters beingchosen to ensure that the cutting edge of the cutter wheel does notpenetrate significantly beyond the material of the outer part of therim.
 4. A can opener as claimed in claim 1 in which the circular flangeand cutter wheel are formed from a single piece of material.
 5. A canopener as claimed in claim 1 in which the circular flange and cutterwheel are jointly mounted about a common axle on which they rotate.
 6. Acan opener as claimed in claim 1 in which the resilient means comprise aresilient rubber washer mounted between the cam means and a stationarysupport.
 7. A can opener as claimed in claim 1 in which the drive wheelhas an outer cylindrical surface which is serrated to allow it to gripinto the material of the rim to assist in driving the can opener aroundthe can, and the lower edge, that is to say the edge adjacent to the lidof the can when in use, of the outer cylindrical surface of the drivewheel is bevelled
 8. A can opener as claimed in claim 7 in which theangle of the bevel is from 30° to 60° to the axis of the drive wheel. 9.A can opener as claimed in claim 7 or claim 8 in which the bevel extendsradially inwardly at the lower edge of the drive wheel by an amount atleast equal to the depth of the serrations.
 10. A can opener as claimedin claim 7 in which the maximum radial depth of the serrations is nomore than 1.5 mm.
 11. A can opener as claimed in claim 10 in which themaximum radial depth of the serrations is no more than 1 mm.
 12. A canopener as claimed in claim 1 in which the drive wheel is supported by ametal shaft which is rotatably journaled within a metal sleeve supportedby the body of the can opener, the outer surface of the shaft and theinner surface of the sleeve mate at positions adjacent the ends of thesleeve so as to provide rotational support for the shaft andintermediate those positions a gap being provided between the outersurface of the shaft and the inner surface of the sleeve to avoidcontact between the shaft and sleeve so as to reduce frictional forcesupon rotation of the shaft relative the sleeve.
 13. A can opener asclaimed in claim 2 which comprises a cutter wheel for engaging andcutting the said outer part of the rim, a rotatable drive wheel forengaging the inner part of the rim, a pair of body members pivoted toone another and arranged, upon pivoting relative one another, to movethe drive wheel and cutter wheel towards and away from one anotherrespectively to allow the can opener to be fitted over the rim of a canto be opened and to grip the rim between the cutter wheel and drivewheel so that, upon rotation of the drive wheel, the can opener orbitsaround the rim of the can and the cutter wheel can complete a cut aroundthe outer part of the rim, the cutter wheel being rotatably supported ona shaft upstanding from one of the body members, a circular flange ofdiameter greater than the cutter wheel also being supported on the saidshaft, and an arcuate support wall upstanding from the said one bodymember and being centered on the axis of rotation of the cutter wheel,the circular flange being arranged to bear against the support wall toassist in supporting the shaft and cutter wheel during cutting of therim of a can.
 14. A can opener as claimed in claim 1 in which the canopener comprises a cutter wheel for engaging and cutting the said outerpart of the rim, a rotatable drive wheel for engaging the inner part ofthe rim, a pair of body members pivoted to one another and havingintegral handles extending generally in a direction away from the pointof pivoting, the body members being arranged, upon pivoting relative oneanother, to move the drive wheel and cutter wheel towards and away fromone another respectively to allow the can opener to be fitted over therim of a can to be opened and to grip the rim between the cutter wheeland drive wheel so that, upon rotation of the drive wheel, the canopener orbits around the rim of the can and the cutter wheel cancomplete a cut around the outer part of the rim, one body membersupporting the cutter wheel and having a substantially flat surface inthe region of the nip between the cutter wheel and the drive wheel, theintegral handle of the other body member having an undersurface which issubstantially flat and also substantially in the same plane as thesubstantially flat surface on the said one body member, whereby when thebody members and their integral handles are pivoted to allow the canopener to be fitted over the rim of a can, those two surfaces will reston the top of the rim of a can and will align the axis of the cutterwheel so that at least in the plane containing them it is parallel withthe upright axis to the can.
 15. A can opener for opening a can having alid joined to a main body by a rim, in which the can is opened bycutting through an outer part of the rim joining the lid with the mainbody of the can, in which the can opener comprises a cutter wheel forengaging and cutting the said outer part of the rim, a rotatable drivewheel for engaging the inner part of the rim, a pair of body memberspivoted to one another and having integral handles extending generallyin a direction away from the axis of pivoting, the body members beingarranged, upon pivoting relative one another, to move the drive wheeland cutter wheel towards and away from one another respectively to allowthe can opener to be fitted over the rim of a can to be opened and togrip the rim between the cutter wheel and drive wheel so that, uponrotation of the drive wheel, the can opener orbits around the rim of thecan and the cutter wheel can complete a cut around the outer part of therim, one body member supporting the cutter wheel and having asubstantially flat surface in the region of the nip between the cutterwheel and the drive wheel, the integral handle of the other body memberhaving an undersurface which is substantially flat and alsosubstantially in the same plane as the substantially flat surface on thesaid one body member, whereby when the body members and their integralhandles are pivoted to allow the can opener to be fitted over the rim ofa can, those two surfaces will rest on the top of the rim of a can andwill align the axis of the cutter wheel so that at least in the planecontaining them it is parallel with the upright axis to the can.
 16. Acan opener as claimed in claim 15 in which the said one body memberwhich supports the cutter wheel also has a further contact surface onthe opposite side of the drive wheel from the cutter wheel.